The goal of this proposal is to investigate the organization and circuitry within the hand and digit region of primary somatosensory cortex in nonhuman primates. Hand and digit behavior are defining aspects of object identification in primate behavior, and are central to different types of tool use, typing, texting, and body language. Despite this, little is known regarding the cortical circuitry underlying different stage of sensory (tactile and proprioceptive) processing. This proposal will use multiple anatomical and functional approaches to discover the intra-areal and inter-areal connectivity patterns between functional columns in the hand representation of primary somatosensory areas (3a, 3b, 1, and 2). These approaches will include anatomical tract tracing and functional tract tracing (using optical imaging and fMRI during focal electrical and pulsed near infrared laser stimulation). The role of these circuits during behavior will be examined. These studies will provide invaluable data for incorporation of sensory guidance in manual motor prosthetics, an area in which there is currently little understanding.